Feature #973
closed
Allow TLS 1.0 and 1.1 to be disabled in BCP 195 profile
Added by Marco Eichelberg over 4 years ago.
Updated over 4 years ago.
Description
The default security profile in DCMTK is the "BCP 195 profile" (--profile-bcp195). Currently DCMTK by default negotiates TLS 1.0 or newer for this profile, in order to offer backward compatibility to the older AES profile. A recent publication by the NSA recommends that TLS 1.0 and 1.1 should be disabled because they are sufficiently broken to be considered insecure (see attachment). The non-downgrading and extended BCP 195 profiles already do that, but for the default BCP 195 profile this should be made configurable (e.g. an option like "--enable-backward-compatibility" would enable support for the historic AES ciphersuite and TLS 1.0/1.1, which should be off by default and only enabled when needed for compatibility reasons).
Files
- Assignee set to Marco Eichelberg
A second look at the existing code in dcmtls shows that we already have all options that we need:
- the non-downgrading BCP 195 profile disables TLS 1.0, TLS 1.1 and the AES ciphersuite that provides backward compatibility to the historic AES profile
- the BPC 195 profile enables a fallback to TLS 1.0 and TLS 1.1 and provides backward compatibility to the historic AES profile
In terms of the IHE IT-I Technical Framework, the non-downgrading BCP 195 profile implements the "TLS 1.2 floor using BCP195 Option", and the BCP 195 profile implements the "TLS 1.0 Floor using BCP195 Option". One could think of a BCP 195 profile that supports TLS 1.0 and TLS 1.1 but does not support AES, but since TLS 1.0 and 1.1 must both be considered broken, this is not a desirable implementation choice anyway.
Therefore, the best approach is simply to change the default TLS profile from BCP 195 to the non-downgrading BCP 195 profile.
- Status changed from New to Closed
- % Done changed from 0 to 100
- Estimated time set to 1:00 h
Closed by commit #ce7518d12 (public DCMTK) and #4dccefdf4 (private modules).
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